/Engine/Source/Editor/UnrealEd/Classes/ActorFactories/ActorFactory.h
Validates the input params for SpawnActor and returns the appropriate level to use depending on whether InLevel and/or InSpawnParams.OverrideLevel is passed :
[ULevel](API\Runtime\Engine\Engine\ULevel) * ValidateSpawnActorLevel ( [ULevel](API\Runtime\Engine\Engine\ULevel) * InLevel, const [FActorSpawnParameters](API\Runtime\Engine\Engine\FActorSpawnParameters) & InSpawnParams ) const